Acid-catalyzed polymerization of saccharides is a well-known phenomenon, described in numerous journal articles, books, and patents. Commonly assigned U.S. Pat. No. 3,766,165, (the disclosure of which is hereby incorporated by reference), to Rennhard, teaches that polymers useful as low-calorie food ingredients can be prepared by heating dextrose or maltose, optionally with a minor amount of a polyol, in the presence of food-acceptable polycarboxylic acid catalysts. Commonly assigned U.S. Pat. No. 3,876,794, (the disclosure of which is hereby incorporated by reference), also to Rennhard, claims various foods containing such polymers. The polyglucose prepared according to Rennhard from a mixture of about 89 percent dextrose, 10 percent sorbitol, and 1 percent citric acid is an approved food additive known as "Polydextrose".
As noted by Torres in commonly assigned U.S. Pat. No. 4,622,233 (the disclosure of which is hereby incorporated by reference), Rennhard's polydextrose possesses a slight bitter taste which limits the breadth of its use in foods. U.S. Pat. No. 4,622,233 teaches that the bitter taste of Rennhard's polydextrose was due to the presence of anhydroglucose, and that color and anhydroglucose content can be reduced by treatment with a solvent and a food approved bleaching agent.
In addition U.S. Pat. Nos. 4,948,596 and 4,956,458 teach the purification of polydextrose by solvent extraction and reverse osmosis respectively. Finally, published European Patent Application EP0380248 teaches a modified polydextrose having less than 0.3 mol % of bound citric acid and a method of preparation of the modified polydextrose.
Thus, there is a continuing search in this field of art for methods of improving polydextrose.